Aeromagnetic data, processing, and maps of Fort Irwin and vicinity, California

Abstract

For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit http://www.usgs.gov or call 1-888-ASK-USGS (1-888-275-8747) For an overview of USGS information products, including maps, imagery, and publications, visit http: //www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.Suggested citation: Langenheim, V.E., and Jachens, R.C., 2014, Aeromagnetic data, processing, and maps of Fort Irwin and vicinity, California, chap. I of Buesch, D.C., ed., Geology and geophysics applied to groundwater hydrology at Fort Irwin, California: U. AbstractAeromagnetic data help provide the underpinnings of a hydrogeologic framework for Fort Irwin by locating inferred structural features or grain that influence groundwater flow. Magnetization boundaries defined by horizontal-gradient analyses coincide locally with Cenozoic faults and can be used to extend these faults beneath cover. These boundaries also highlight the structural grain within the crystalline rocks and may serve as a proxy for fracturing, an important source of permeability within the generally impermeable basement rocks, thus mapping potential groundwater pathways through and along the mountain ranges in the study area.

Cenozoic geology of Fort Irwin and vicinity, California

“…The ages are from a variety of citations that include descriptions of methods; the Mesozoic ages are primarily based on U-Pb zircon data (supplemented by K-Ar and 40 Ar/ 39 Ar data where needed), and Cenozoic ages are based on 40 Ar/ 39 Ar data with some tephrochronologic data. Data were also incorporated from a variety of geophysical techniques including analysis of resistivity from laboratory electromagnetic measurements (LEM) (Bloss and Bedrosian, 2015), field-based time-domain electromagnetic (TEM) surveys (Burgess and Bedrosian, 2014), airborne electromagnetic (AEM) surveys (Bedrosian and others, 2014), and gravity and aeromagnetic surveys (Jachens and Langenheim, 2014;Langenheim and Jachens, 2014). The geophysical techniques are described in detail in the other chapters in this report.…”

Geologic map and borehole stratigraphy of Hinkley Valley and vicinity, San Bernardino County, California

“…Another application of this technique was applied to the Fort Irwin region, mostly to the northeast of the map area, by Jachens and Langenheim (2014), using a 250-m grid and independent constraints of depth to pre-Cenozoic basement. A companion paper (Langenheim and Jachens, 2014) to the Jachens and Langenheim (2014) study also [Geochemical values in percent. Mtn, Mountain] compiled and analyzed aeromagnetic data of the Fort Irwin region to ascertain structural grain, map concealed faults, and point out long-term fault offset by correlating offset magnetic features.…”